As the surface finishing machine for finishing various roller surfaces by using lapping film abrasives, the device disclosed in the Jan. 1987 issue of the monthly publication "Machine Technology" is known.
In this machine, the lapping film which is taken up in the opposite direction of the roller rotating direction, that is, in a specific direction is pressed against the roller surface (the surface to be polished) by the contact roller reciprocatable in the roller axial direction, and the roller surface is uniformly finished.
However, in such composition as this conventional machine in which the lapping film taken up in one direction is pressed against the surface to be polished of the work (roller) rotating in the opposite direction to polish, if the surface to be polished of the work is a curved surface having an arc-shaped section with a small radius of curvature, such as the slipper surface of the rocker arm, the rate of the length of the portion of the lapping film passing through without being used in polishing of this curved surface with respect to the length of the portion of the lapping film used in polishing of the curved surface is extremely large, and the lapping film is spent wastefully.
On the other hand, when it is designed so that the work oscillates around the center of oscillation, the lapping film is advantageously stretched taut when the oscillating direction of the work is opposite to the moving direction of the lapping film, but when the both moving directions are same and the oscillation speed of the work is high, the lapping film is excessively drawn out from the feed spool side. Accordingly it may be sometimes impossible to polish while keeping the tension of the lapping film on the surface to be polished of the work.
Or, in the conventional structure of taking up the lapping film in one direction, when the lapping film once used in polishing is exchanged with a new lapping film on every occasion of use, the polishing work is interrupted by each exchange, and the working efficiency is significantly lowered.
Still more, in the structure of pressing the lapping film against the surface to be polished of the work by the contact roll, if there is a slight curvature in the widthwise direction in the work such as polishing of a curved surface of slipper surface of rocker arm as mentioned above, polishing along the surface to be polished curved in the widthwise direction becomes impossible.